fig10
![Alkali pretreatment effects on acid leaching recovery of rare earth elements from coal waste of the Western Kentucky No. 13 and Fire Clay seams](https://image.oaes.cc/020683d7-f854-43cd-b83e-bde768784680/4853.fig.10.jpg)
Figure 10. XRD patterns of the raw, alkali-pretreated, and alkali-pretreated, acid-leached coal wastes of the (A) Western Kentucky No. 13 and (B) Fire Clay seams. (Alkali pretreatment conditions: 5 M NaOH at 90 °C; acid leaching conditions: 1.2 M HCl at 90 °C). XRD: X-ray diffraction.